Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.
Plant Physiol. 2022 Oct 27;190(3):1658-1672. doi: 10.1093/plphys/kiac396.
Depending on their fatty acid (FA) chain length, triacylglycerols (TAGs) have distinct applications; thus, a feedstock with a genetically designed chain length is desirable to maximize process efficiency and product versatility. Here, ex vivo, in vitro, and in vivo profiling of the large set of type-2 diacylglycerol acyltransferases (NoDGAT2s) in the industrial oleaginous microalga Nannochloropsis oceanica revealed two endoplasmic reticulum-localized enzymes that can assemble medium-chain FAs (MCFAs) with 8-12 carbons into TAGs. Specifically, NoDGAT2D serves as a generalist that assembles C8-C18 FAs into TAG, whereas NoDGAT2H is a specialist that incorporates only MCFAs into TAG. Based on such specialization, stacking of NoDGAT2D with MCFA- or diacylglycerol-supplying enzymes or regulators, including rationally engineering Cuphea palustris acyl carrier protein thioesterase, Cocos nucifera lysophosphatidic acid acyltransferase, and Arabidopsis thaliana WRINKLED1, elevated the medium-chain triacylglycerol (MCT) share in total TAG 66-fold and MCT productivity 64.8-fold at the peak phase of oil production. Such functional specialization of NoDGAT2s in the chain length of substrates and products reveals a dimension of control in the cellular TAG profile, which can be exploited for producing designer oils in microalgae.
根据其脂肪酸 (FA) 链长，三酰基甘油 (TAG) 具有不同的应用；因此，需要一种具有遗传设计链长的原料，以最大限度地提高工艺效率和产品多功能性。在这里，对工业产油微藻海洋盐藻中的大型 2 型二酰基甘油酰基转移酶 (NoDGAT2) 进行了离体、体外和体内分析，揭示了两种内质网定位的酶，它们可以将 8-12 个碳原子的中链脂肪酸 (MCFA) 组装成 TAG。具体来说，NoDGAT2D 是一种将 C8-C18 脂肪酸组装成 TAG 的多面手，而 NoDGAT2H 是一种仅将 MCFAs 组装成 TAG 的专家。基于这种专业化，将 NoDGAT2D 与提供 MCFA 或二酰基甘油的酶或调节剂（包括合理工程化的 Cuphea palustris 酰基辅酶 A 硫酯酶、Cocos nucifera 溶血磷脂酸酰基转移酶和 Arabidopsis thaliana WRINKLED1）叠加，可以将总 TAG 中的中链三酰基甘油 (MCT) 份额提高 66 倍，MCT 生产率提高 64.8 倍，在产油高峰期。NoDGAT2s 在底物和产物的链长上的这种功能专业化揭示了细胞 TAG 谱中控制的一个维度，这可以用于在微藻中生产设计油。
